Alkali metal alkylaryl sulfonate compositions



United States Patent O US. Cl. 252161 8 Claims ABSTRACT OF THE DISCLOSURE Non-caking detergent compositions comprising an admixture of an alkali metal lower alkyl naphthalene sulfonate and a biodegradable normal alkyl benzene sulfonate. The naphthalene compound functions as an anticaking agent for the normal alkyl benzene sulfonate.

This is a continuation of application Ser. No. 463,325, filed June 11, 1965, now abandoned.

This invention is concerned with novel compositions suitable for use in detergent formulations. More particularly, this invention is concerned with biodegradable alkylaryl sulfonate compositions characterized by improved handling: and drying properties which are suitable for use in detergent formulations.

The recent demand for biodegradable surfactants has lead to the use of alkali metal sulfonates of alkylated benzenes containing a secondary higher n-alkyl group, I

which may be represented by the formula:

MSO (B wherein M is an alkali metal, such as sodium, potassium, lithium, ammonium and the like, preferably sodium; R is a higher secondary n-alkyl group of from about 5 to 17 carbons; R is an alkyl group, such as methyl, ethyl or a secondary n-alkyl group of from 3 to about 8 carbons, but no more carbons than R; n is an integer of from 0 to 2 inclusive; and the total carbons in R and (R is in the range of from about 8 to about 18, preferably 10 to about 15. Illustrative examples include alkylbenzene sulfonates, alkylt-oluene sulfonates, alkylxylene sulfonates, alkylethylbenzene sulfonates, diheptylbenzene sulfonates and the like. Preferred higher alkylbenzene sulfonates are the monoalkylbenzene sulfonates and the monoalkyltoluene sulfonates of the formula:

MSO M;

wherein R is secondary n-alkyl of from 9 to 17 carbons; M is an alkali metal; and m is an integer having a value of from 0 to l, inclusive.

These higher alkylbenzene sulfonates, by the proper selection of isomers and homologs and the proper blending of individual compounds, can be readily substituted for the previously-employed hard alkylbenzene sulfonates in detergent formulations without loss of detergent or foaming properties. However, in all cases the 'bio degradable alkylbenzene sulfonates suffer from poorer handling properties, and are more difficult to formulate than the hard alkylbenzene sulfonates.

The higher-n-alkylbenzene sulfonates are normally supplied to the formulator in the form of 30 to 200 mesh flakes of high active, generally at least weight percent, material, with the balance being inorganic sulfate salts. These flakes are produced by drying the aqueous slurry from the sulfonation of the alkylbenzene and neutralization of the resulting sulfonic acid, followed by particle size reduction and screening. The sized high active flake is then charged to fiber drums for transport to the shipper. A typical recovery technique comprises drying the slurry on a drum dryer to form a sheet which is fed to a screw conveyor, which breaks the sheet to flake and conveys the flake to the screens for the sizing operation. Higher-n-alkylbenzene sulfonates are not readily processable to flake by this technique. First, the slurry cannot be dried on conventional drum dryers to form a crisp, friable sheet, but, rather, forms a tacky, often wax-like sheet, which plugs the screw conveyor. Secondly, the tacky higher-n-alkylbenzene sulfonate plugs the screen. Finally, on storage, the particulate higher-n-alkylbenzene sulfonate tends to cake, often forming a solid mass in a few days.

Previously sodium toluene or xylene sulfonates had been employed as anti-caking additives for the hard alkylbenzene sulfonates. However, these materials were required in fairly large amounts, often about 5 percent, to substantially inhibit caking, thus precluding the supplying of alkylbenzene sulfonates in high active form. Further, when these additives are employed with secondary-n-alkylbenzene sulfonates, little or no anti-caking activity is observed even in amounts as high as 5 percent.

It has been unexpectedly and surprisingly discovered by this invention that certain alkali metal lower-alkylnaphthalene sulfonates are exceptionally effective anticaking agents for the biodegradable alkylaryl sulfonates. These alkali metal lower-alkylnaphthalene sulfonates are represented by the general formula:

wherein M is an alkali metal; each R and R is a lower alkyl group of no more than 4 carbons, preferably methyl; each w and x is an integer having a value of from 0 to 2, inclusive, and each y and z is an integer having a value of from 0 to 1, inclusive, with the proviso that the sum of (w+x) is at least 1 and the sum of (y-l-z) is 1. Illustrative compounds include sodium l-methylnaphthalene sulfonate, potassium lamethylnaphthalene sulfonate, ammonium l-methylnaphthalene sulfonate, sodium Z-methylnaphthalene sulfonate, sodium l-ethylnaphthalene sulfonate, sodium l-propylnaphthalene sulfonate, sodium dimethylnaphthalene sulfonate, sodium trimethylnaphthalene sulfonate, sodium diethylnaphthalene sulfonate, sodium methylethylnaphthalene sulfonates and the like. Sodium monomethylnaphthalene sulfonates are preferred.

The effective amount of alkali metal Iower-alkylnaphthalene sulfonate is in the range of from about 0.01 to about 1 weight percent, based' upon the weight of higheralkylbenzene sulfonate. Amounts of less than about 0.01 weight percent are generally ineffective. The optimum amount of lower-alkylnaphthalene sulfonate is from about 0.05 to about 0.1 weight percent.

The lower-alkylnaphthalene sulfonate can be incorporated in the higher-alkylbenzene sulfonate in any suitable manner provided it is prior to drying the aqueous slurry from the neutralization of the higher-alkylbenzene sulfonic acid. A preferred technique comprises admixing a lower-alkylnaphthalene with the higher-alkylbenzene fed to the sulfonation reaction, thereby forming the alkali metal lower-alkylnaphthalene sulfonate in situ during the production of the alkali metal higher-alkylbenzene sulfonate. In this manner thorough dispersion of the loweralkylnaphthalene sulfonate throughout the higher-alkylbenzene sulfonate is assured.

The following examples are illustrative.

EXAMPLE 1 To an aqueous slurry containing 50 weight percent of a mixture of 86.4 weight percent sodium secondary alkylbenzene sulfonate having alkyl groups of from 10 to 14 carbons and averaging 11.5 carbons and 13.6 weight percent sodium sulfate was added a mixture of the sodium sulfonates of l-methylnaphthalene and 2-methylnaphthalene in amounts of 0.05 or 0.1 weight percent, based on sodium alkylbeuzene sulfonate. The resulting slurry was dried, flaked and screened to 30 to 100 mesh particles. Employing the test procedure of H. Watanabe et al., Caking Test for Dried Detergents, I. Am. Oil Chem. Soc., 41, 31115 (1964), each formulation was molded into a 60-61 millimeter long by 2-inch diameter cylinder at a compression rate of 0.5 inch per minute to 80 p.s.i. and then resting for 5 minutes. The molded cylinder was then compressed at a rate of 0.5 inch per minute to yield or break. At a 1.6 percent moisture level, the sample containing 0.05 weight percent sodium methylnaphthyl sulfonate broke at 18 pounds, and, at a moisture level of 1.8 percent, the sample containing 0.1 weight percent sodium methylnaphthalene sulfonate broke at 15 pounds. The yield forces for the sodium alkylbenzene sulfonate without added sodium methylnaphthalene sulfonate at moisture levels of 1.6 and 1.8 percent were 28 and 33 pounds, respectively.

EXAMPLE 2 To 2100 pounds of an aqueous slurry containing 43 weight percent of a sodium sulfonate of a mixture of secondary n-alkylbenzenes having alkyl groups of from to 14, carbons and averaging 11.5 carbons and 8 weight percent sodium sulfate, was added 386 grams of a mixture of the sodium sulfonates of l-methylnaphthalene and 2- methylnaphthalene in the form of a 20 percent aqueous solution. The resulting slurry was dried in a drum dryer at a rate of 240 pounds of slurry per hour to provide a crisp, friable sheet which did not plug the screw conveyor and screens employed in reducing the alkylbenzene sulfonate to small particles. The resulting particles, which contained 85 percent active alkylbenzene sulfonate, were crisp and could not be compacted into a lump or ball on squeezing by hand. The particles were then charged to 160-pound capacity fiber drums. The drums were sealed and stored for 10 days, at which time the product was free flowing and was free of significant amounts of lumps or agglomerates.

In a similar test, except that the sodium methylnaphthalene sulfonate was not added, the slurry could not be readily dried, and formed a sticky wax-like sheet which plugged the screw conveyor and screens. The resulting particles were readily squeezed by hand to form a compact ball, and on storage for ten days formed a solid mass.

What is claimed is:

1. A dry, non-caking, particulate composition consisting essentially of an admixture of (1) an alkali metal higher-alkylbenzene sulfonate of the formula:

wherein M is an alkali metal; R is a secondary n-alky] group of from 5 to 17 carbons; R is a member selected from the group consisting of methyl, ethyl and secondary n-alkyl of from 3 to 8 carbons, but no more carbons than 4 R; n is an integer of from 0 to 2; and the total carbons in R and (R is in the range of from 8 to 18, and (2) an effective amount of an alkali metal lower-alkylnaphthalene sulfonate of the formula:

wherein M is an alkali metal; each R and R is a lower alkyl group of no more than 4- carbons; each w and x is an integer having a value of from 0 to 2; and each y and z is an integer having a value of from 0 to 1, with the proviso that the sum of (w+x) is at least 1 and the sum of (y-l-z) is 1, said effective amount being an amount suf ficient to inhibit the caking tendency of said alkali metal higher-alkylbenzene sulfonate.

2. A dry non-caking, particulate composition consisting essentially of an admixture of (1) an alkali metal higher-alkylbenzene sulfonate of the formula:

NaSO (0 3)m wherein R is a secondary n-alkyl group of from 9 to 17 carbons; and m is an integer having a value of 0 to 1, and (2) an effective amount of an alkali metal loweralkylnaphthalene sulfonate of the formula:

( Ha)w 3):

(NaSOa)y 3 01 wherein each w and x is an integer having a value of from 0 to 2; and each y and z is an integer having a value of from 0 to 1, with the proviso that the sum of (w-i-x) has a value of at least 1, and the sum of (y-l-z) has a value of 1, said effective amount being an amount sufficient to inhibit the caking tendency of said alkali metal higher-alkylbenzene sulfonate.

3. A dry, non-caking, particulate composition consisting essentially of an admixture of 1) an alkali metal higher-alkylbenzene sulfonate of the formula:

wherein M is an alkali metal; R is a secondary n-alkyl group of from 5 to 17 carbons; R is a member selected from the group consisting of methyl ethyl and secondary n-alkyl of from 3 to 8 carbons, but no more carbons than R; n is an integer of from 0 to 2; and the total carbons in R and (R is in the range of from 8 to 18, and (2) from 0.01 to 1 weight percent, based upon said higher-alkylbenzene sulfonate, of an alkali metal loweralkylnaphthalene sulfonate of the formula:

wherein M is an alkali metal; each R and R is a lower alkyl group of no more than 4 carbons; each w and x is an integer having a value of from 0 to 2; and each y and z is an integer having a value of from 0 to 1, with the proviso that the sum of (w-l-x) is at least 1 and the sum of (y +z) is 1.

5 4. A dry, non-caking, particulate composition consisting essentially of an admixture of (1) an alkali metal higher-alkylbenzene sulfonate of the formula:

NaSOa Q-n wherein R is a secondary n-alkyl group of from 9 to 17 carbons; and m is an integer having a value of to l, and (2) from 0.05 to 0.1 weight percent, based upon said alkali metal higher-alkylbenzene sulfonate, of an alkali metal lower-alkylnaphthalene sulfonate of the formula:

(NaS0a)y (SO Na),

MSO (B wherein M is an alkali metal; R is a secondary n-alkyl group of from to 17 carbons; R is a member selected from the group consisting of methyl, ethyl and secondary n-alkyl of from 3 to 8 carbons, but no more carbons than R; n is an integer of from 0 to 2; and the total carbons in R and (R is in the range of from 8 to 18, by drying an aqueous slurry of said alkali metal higher-alkylbenzene sulfonate and forming particles of reduced size, the improvement of prior to said drying adding to said slurry an amount effective to inhibit the caking tendency of said alkali metal higher-alkylbenzene sulfonate of an alkali metal lower-alkylnaphthalene sulfonate of the formula:

(M803) y 3 I wherein M is an alkali metal; each R and R is a lower alkyl group of no more than 4 carbons; each w and x is an integer having a value of from 0 to 2; and each y and z is an integer having a value of from 0 to 1; with the proviso that the sum of (w,+x) has a value of at least 1 and the sum of (y+z) has a value of l.

6. The process as claimed in claim 5 wherein said lower-alkylnaphthalene sulfonate is incorporated into said slurry by the sulfonation and neutralization of a mixture of the compounds of the formulae:

where R, R, n, w and x have been defined in claim 51 7. In the process consisting essentially of producing a dry, particulate solid alkali metal higher-alkylbenzene sulfonate of the formula:

NaSO (CHQH wherein R is a secondary n-alkyl group of from 9 to 17 carbons; and n is an integer having a value of from 0 to 1, by drying an aqueous slurry of said alkali metal higher-alkylbenzene sulfonate and forming particles of reduced size, the improvement of prior to said drying adding to said slurry an amount effective to inhibit the caking tendency of said alkali metal higher-alkylbenzene sulfonate of an alkali metal lower-alkylnaphthalene sulfonate of the formula:

( sh (803N101 wherein R, R, n, w and x are defined in claim 7.

References Cited UNITED STATES PATENTS 2,944,028 7/1960 Stayner 252-161 3,116,185 12/1963 Wilson et al 252-383 3,328,314 6/1967 Marquis 252-383 LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner US. Cl. X.R. 252-384 

